After the deployment and till the landing, the skydiver or tandem passenger, supported by his harness, has a substantially upright position. However, this position, which is well adapted to the deployment phase, is not well adapted to the canopy descent and particularly to long duration flight. Indeed, the suspension of the body in upright position without any support does not promote the blood circulation and increases the drag, whereas a more seated position wherein the lower body is tilted to 90° toward the front with respect to the upper body, to get closer to an horizontal position of the thighs, thus not extending from the chest vertical direction, is more appropriate for the cardiovascular system, the comfort and the drift performance during canopy drift. Unfortunately, it is not possible to take without effort such a position with known harnesses and currently used strap fixation systems in skydiving because the strap and buckle arrangement makes such an important variation of the position during the canopy descent impossible.